1HZ internal differences (2 Viewers)

[Bryan062087]

Hi all,

I recently came across a few forum posts which indicated that 1HZ engines from 105 series models had weaker internals than the same engine found in other models--perhaps 70 and 80 series trucks. Can anyone elaborate on these differences, if they are in fact true?

Thanks.

 

[Hulsty]

Lighter pistons amoung one of the items changed, EGR too

 

[roscoFJ73]

I havent heard of anything affecting their longevity and Ive never heard of weeker parts. I guess the 78/79 series and Coasters would be the same if it was true.

 

[mudgudgeon]

Lighter pistons, and they definitely have a reputation for disliking a turbo.
Turbo at your own risk

 

[GTSSportCoupe]

Lighter pistons, and they definitely have a reputation for disliking a turbo.
Turbo at your own risk

That's what I've read too.

 

[wedgetail]

Yes lighter pistons, but nothing else. Only got egr from late 2002 on.

 

[Gengis]

2007 in South Africa still had no EGR. And I would have blanked if it had. Lighter pistons would mean less rotating mass and free'er reving. I have never driven an older one, but this one revs well, and is no slouch off the mark.

 

[roscoFJ73]

Looking through the parts diagrams, it seems the change to different pistons was not uniform. Some Coasters retained the old piston until 2016 and some 80 series were still using them in 2001
And some 105 series, until 2002, were still using the same pistons as other 1HZ from 1993 (HZJ75 ARL)
This part number 13101-17100-01 was 1st used in 1990 on EUR and ARL 1HZ's and ceased on 93. Then on some 76,78,79, they started using it 2016 in GEN and GCC

So unless you know the exact model, year and market of the 1HZ , you wont probably know what pistons are in there until you strip it down.